Ben Coccio wanted to make a movie that fused the you-are-there style of The Blair Witch Project with the all-too-real horror of the Columbine killings. Zero Day, his first feature, puts a video camera in the hands of a pair of high-school loners, Cal and Andre, and follows their "army of two" assault on their classmates. "I don't know why I was so compelled to make this movie," Coccio admits. "But I was attracted to the relationship and the tragic, Shakespearean proportions of their decision to have this dark plan and follow through on it."

The title refers to the fateful date the boys pick to go on a Columbine-style rampage. The plan is hatched one night, with the soldiers' first act of war amounting to no more than a childish prank (they egg the house of a popular kid). Soon, however, they're stealing guns and burning their CDs and video games, taping everything as they go. "I really love having a first-person narrative," Coccio says. "It's a similar approach to Blair Witch Project, but it calls attention to the contrast between horror and real horror.

"People are recording moments a lot more. It's the idea of making your own reality TV show: If I document this, I'm significant. I'll be watched. I'll be seen. I'll be understood."

The video-diary premise -- the tapes are made by the boys and stored in a safety deposit box to be opened after their rampage -- isn't a novel one. But Coccio, who co-wrote the film, lets Zero Day unravel almost naturally -- including both the mundane (Cal gets his braces removed) and the chilling (the massacre is meticulously planned in Andre's parents' bedroom).

Adding to the authenticity is the movie's amateur cast. The two leads are played by Connecticut teenagers named Cal and Andre, and their parents are portrayed onscreen by their real moms and dads. "They took what I had written and said it in their own words," Coccio says. "I told them, 'You've got to say this, and then you've got to say this. But to get from Point A to Point B, say what you think.'"

It's also a factor that makes Zero Day a more intimate and unsettling film than Gus Van Sant's Elephant. "We get to a similar place," Coccio says. "But it's a completely different approach. I wanted to have a present feeling of reality. You don't get to know Gus Van Sant's shooters. I never give a reason why [my characters] have to do this awful thing, but you do get to know them.

"It's hard to say this, but I think I have to sympathize with them," Coccio adds. "I didn't want to demonize these kids or turn them into monsters. I just tried to portray them honestly, without making excuses for them. At the same time, I didn't want to simplify why something like this might happen."